The present invention relates to a hand-guided work tool, especially a motor chainsaw, a cut-off saw, etc., comprising an internal combustion engine with an ignition system which comprises a pole wheel mounted on the crankshaft of the internal combustion engine and having permanent magnets positioned about the periphery in a sequential arrangement. The ignition system further comprises a plurality of charge armatures connected to the housing which close a magnetic circuit between the poles of the permanent magnets. The legs of the charge armatures support excitation coils and the permanent magnets of the pole wheel induce in the excitation coils of the charge armatures an electrical current which is supplied to the carburetor heater and a grip heater of the work tool.
The electrical energy for the ignition system of the internal combustion engine of motor chainsaws is, in general, generated by a pole wheel revolving with the crankshaft and having permanent magnets arranged in the circumferential direction in a row after one another that generate an electrical current in the excitation coils of charge armatures connected to the housing. The excitation coils are connected in series and together supply, among other consumers, a grip heater and a carburetor heater of the motor chainsaw in order to allow use of the chainsaw at low temperatures. The available power output of the generator is thus divided to the grip and to the carburetor depending on the resistance ratios of the respective heat coils. When only one of the two heaters is in use, it is supplied with a very high power output which for carburetor heaters can result in excessive temperatures and thus in fuel vapor bubble formation within the carburetor. When the windings of the excitation coil are adjusted to achieve a certain heating output for the carburetor, an insufficient total output is provided when the carburetor heater and the grip heater are operated simultaneously so that especially the grip heater will not operate satisfactorily, i.e. the temperature achieved is then too low. When adjusting the output by using different load resistors, negative effects in the heating circuits will occur during operation because of the electrical coupling in the coil resistors of the generator and the magnetic coupling in the magnetic circuit.
The invention has the object to improve a hand-held portable work tool with an internal combustion engine such that the carburetor heater and the grip heater can be supplied with respectively adjusted electrical energy.